1. Field of the Invention
The present invention pertains to endoscopic portals for establishing communication with an internal site in a body cavity and, more particularly, to endoscopic portals having expandable cannulas providing a variable size lumen or passage through a cavity wall and to methods of establishing a passage through a cavity wall utilizing such endoscopic portals.
2. Discussion of the Related Art
In endoscopic procedures, a sleeve or cannula or other structure forming a passage is normally disposed in a body cavity wall such that a distal end of the cannula is positioned within the body cavity and a proximal end of the cannula is disposed externally of the body cavity with the lumen of the cannula providing a passage establishing communication with an internal site from externally of the body cavity. Typically, various instruments are introduced at the internal site through the passage of the cannula in order to perform diagnostic and/or surgical procedures, with the instruments many times having varying sizes in cross section. Since the passages of the cannulas are usually of fixed cross sectional size, it is necessary in a given procedure to utilize a cannula having a lumen large enough to accommodate the largest size instrument to be introduced in the body cavity. Accordingly, a puncture or opening is typically made through the cavity wall large enough to accommodate the cannula being used, and such opening may be larger than necessary when the instruments actually introduced are smaller in cross sectional size than the cross sectional size of the lumen. The sizes of punctures or openings in the cavity wall required to accommodate fixed size conventional cannulas in general necessitate performance of the endoscopic procedures at hospital sites. In order to reduce trauma and shorten recovery times for patients, to expand the use of non-hospital or outpatient sites for endoscopic procedures and to reduce costs, among other reasons, it would be desirable to begin an endoscopic operative procedure with as small a cannula as possible to minimize the size of the puncture or opening and to thereafter expand the cannula to non-traumatically stretch or dilate the puncture or opening to accommodate larger size instruments and/or anatomical specimens, such as organs, to be introduced in and/or withdrawn from the body. However, with endoscopic portals having fixed size cannulas, non-traumatic dilatation of the puncture or opening is not possible. Another disadvantage of presently utilized endoscopic portals is that the cannulas are not self-penetrating but require a separate penetrating member or obturator for penetrating the cavity wall.
It is important in endoscopic procedures to prevent undesired fluid flow to and from the internal site; and, accordingly, the endoscopic portals must be sealed prior to and subsequent to the introduction of instruments and while the instruments are in place. In particular, fluids such as gaseous phase carbon dioxide or nitrous oxide are normally introduced in the body for insufflation as part of the endoscopic procedure, and the escape of such gases through the endoscopic portal should be prevented. With fixed size cannulas, the size of instruments that can be introduced through the lumen is limited since instruments having a cross sectional size larger than the fixed cross sectional size of the lumen cannot be fit through the lumen; and, when instruments smaller in cross sectional size than the fixed cross sectional size of the lumen are introduced, a seal is not formed with the introduced instruments. Since the cross sectional size of the lumen must be large enough to accommodate the largest size instrument to be introduced in a procedure, there is a gap between the cannula and smaller size instruments introduced therethrough through which fluid can escape. Many endoscopic portals have valves to prevent leakage of fluid , such valves including one or more valve passages typically of fixed cross sectional sizes. The sizes of instruments that can be introduced in the valve passages is limited since fluids can escape past instruments having cross sectional sizes that do not correspond to the fixed cross sectional sizes of the valve passages. Universal seals having variable size passages for receiving and sealingly engaging instruments of various sizes have been proposed for endoscopic portals. Many of the universal seals proposed for endoscopic portals have various drawbacks including structural and functional complexity, the need for a separate seal housing, adding to the overall length of the endoscopic portals, and failing to provide adequate support for introduced instruments.
It is also desirable in endoscopic procedures that the cannula be stabilized relative to the cavity wall to prevent backing out of the cannula from the body cavity. Although stabilizers for endoscopic portals have been proposed, most present various drawbacks due to their structural and operational complexity. In addition, conventional stabilizers typically do not afford stabilization relative to a primary cavity as well as a secondary cavity disposed in the primary cavity as would be desirable for cavity in a cavity procedures.